Characterization of Reinforced Asphalt Pavement Structures Built over Organic Soils Employing Falling Weight Deflectometer

Many regions throughout Florida have shallow layers of plastic and organic soils under existing roadways. Due to low strength and extremely high compressibility characteristics of these soils, most of the roads built over these subgrades frequently exhibit vast amount of cracking, distortion, rutting and differential settlement, curtailing their useful life. This paper presents a case study in the use of a variety of pavement reinforcing products in an effort to alleviate excessive pavement distortion and degradation resulting from unstable foundation. A total of 24 test sections (each 500 feet long) were constructed which included 8 control sections, and 16 reinforced asphalt sections containing Glasgrid, PetroGrid, PaveTrac and Asphalt Rubber Membrane Interlayer (ARMI), at 2 different test locations representing significantly different site characteristics. Prior to rehabilitation, Falling Weight Deflectometer (FWD) tests were conducted at every 50 feet along the proposed test section alignment for evaluating the existing pavement capacity, and statistically determining the site variability among the test sections. Six months after the reconstruction project, FWD tests were repeated at the same locations ascertaining relative performance improvements of the test sections. The stiffness/strength of the test sections increased moderately, owing primarily to the reinforcements. The pavement performance over time, however, could be different depending on several factors, such as interlock between the grid and the asphalt and the restraint provided by each reinforcement; therefore, monitoring will continue for several years.